Needle clamps for sewing machines



Jan. 9, 1962 w. D. SZUBA 3,016,031

NEEDLE CLAMPS FOR SEWING MACHINES Filed Aug. 27, 1958 2| 2o H H l9 Fig.2

20 2| 6 LKQ: ea 2 INVENTOR. Walfer D. Szuba A TOR N EY WITNESS r a: a.

United States Patent Ofiice Bil-16,031 Patented Jan. 9, 1962 3,016,031 NEEDLE CLAMPS FOR SEWING MACHINES Walter D. Szuba, Summit, N.J., assignor to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Filed Aug. 27, 1958, Ser. No. 757,609 1 Claim. (Cl. 112-226) The present invention relates to a needle clamp for securing a needle to the needle bar of a sewing machine and more particularly, a needle clamp which is designed for use in a sewing machine in which the needle is threaded from left to right.

The objects of this invention are to provide such a needle clamp which, in addition to its normal function of securing the needle to the needle bar, will also prevent insertion of the needle in other than the correct sewing position, and which at the same time, is economical to manufacture and simple to handle in assembling it on the needle bar.

There is disclosed and claimed in the United States patent of Johnson, No. 2,698,589, a sewing machine needle clamp which is designed so that a needle cannot be inserted in other than the correct sewing position. The embodiment of the invention illustrated in that patent is limited to use in sewing machines in which the needle is threaded from right to left. The direction in which the needle of a sewing machine is threaded depends upon the characteristics of the loop-taker mechanism. In all cases, however, the needle thread loop is always seized by the loop-taker on the short groove side of the needle and to obtain the proper alignment of the needle relatively to the loop-taker the needle is provided wtih a positioning face or flat on the shank which is on the same side of the needle as the short groove. In a sewing machine as illustrated in the Johnson patent, the loop-taker passes to the left of the needle at loop seizure so that the short groove side of the needle and the positioning face are to the left and the needle is threaded from right to left. In a sewing machine in which the loop-taker passes to the right of the needle at loop seizure, the short groove side of the needle and the positioning face are at the right and the needle is threaded from left to right. However, the thumb screw of the needle clamp is universally used on family sewing machines to drive the sewing machine attachments, and these attachments have been standard zed to be driven by a thumb screw disposed at the right of the needle bar. Thus, from the standpoint of accommodating standard sewing machine attachments, the thumb screw of the needle clamp must be at the right and consequently, the embodiment of the needle clamp illustrated in the Johnson patent cannot be used in a machine in which the needle is threaded from left to right. In accordance With the present invention, there has been provided a needle clamp which is specifically designed for use in such a machine.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary vertical sectional view of a needle bar having a needle clamp in accordance with the invention.

FIG. 2 is a horizontal sectional view taken substantially on the line 22 of FIG. 1.

FIG. 3 is a fragmentary elevational view of the needle bar and needle clamp of FIG. 1 as seen from the left hand side as appearing in FIG. 1.

FIG. 4 is a detail view in perspective of the gib per se of the needle clamp of FIG. 1.

As illustrated in the drawings, the needle bar 1 of a sewing machine has in the lower end thereof a radial slot 2 extending endwise of the needle bar 1 and defined by a flat bottom 3 and parallel sides 4. The needle 5 has a shank 6 at the upper end thereof that is formed as a right circular cylinder having a slabbed side 7 which constitutes the positioning face. Since the present invention relates to a needle clamp for a sewing machine in which the needle is threaded from left to right, the slot 2 extends radially into the lower end of the needle bar 1 from the left and the positioning face 7 of the needle 5 is placed at the right. The needle 5 is positioned endwise of the needle bar 1 by a positioning pin 8 arranged transversely of the needle bar 1 and extending into the slot 2.

To secure the needle 5 to the needle bar 1, there is provided a needle clamp including a gib 9 having a central cylindrical portion 10 and oppositely extending arms 11. The central portion 10 has a diameter that is greater than the width of the slot 2 but less than the diameter of the needle bar 1 and the arms 11 are only wide enough so that they can be loosely accommodated in the slot 2. The needle engaging face 12 of the central portion 10 is flat and is provided with a groove 13 that is shaped to conform to the curved portion of the needle shank 6. The needle bar 1 has a circular bore 14 of a diameter large enough to accommodate the central portion 10 of the gib 9, which bore 14 extends radially inwardly from the same side of the needle bar 1 as the slot 2 and which intersects the slot 2. The gib 9 is mounted on the needle bar 1 with the central portion 10 in the bore 14 and the arms 11 in the slot 2, the arms 11 serving to prevent turning of the gib 9 in the bore 14.

To force the gib 9 inwardly and thus to clamp the needle against the bottom 3 of the slot 2, there is provided a needle clamp body 15 having a through-bore 16 that is larger than the diameter of the needle bar 1. The body 15 is placed on the needle bar 1 with the needle bar ex tending through the b0re'16 so that the body 15 surrounds the needle bar and the central portion 10 of the gib 9. The gib 9 has the outer face 17 of the central portion 10, which is the face opposite from the needle engaging face 12, formed to conform to the periphery of the needle bar 1 and the central portion 10 is dimensioned so that when the groove 13 is in needle clamp ing position, the outer face 17 slightly protrudes beyond the periphery of the needle bar. At a point opposite from the gib engaging portion of the needle clamping body 15 there is a boss 18 through which is threaded a thumb screw 19, the end of which engages against the periphery of the needle bar 1 to tension the body 15 and thereby pull the gib 9 inwardly of the needle bar into needle clamping position.

With the central portion 10 disposed in the bore 14, the gib 9 is held against movement endwise of the needle bar 1 and is held with the central portion 10 in the bore 14 by the neeedle clamping body 15. The body 15 is then secured to the gib 9 against movement endwise of the needle bar 1 by a screw 20 which is threaded through the same and has a stud 21 that extends into a bore 22 in the central portion 10 of the gib.

The needle 5, when it is inserted into the slot 2, is arranged with the positioning face 7 against the fiat bottom 3 of the slot and is abutted endwise against the pin 8. To prevent improper insertion of the needle, advantage is taken of the fact that the slabbed shank 6 of the needle has a minor transverse dimension represented by the diameter of the shank that intersects the center point of the positioning face 7 and a major transverse dimension represented by a diameter that is at a right angle to the minor diameter or in other words, parallel to the positioning face 7. The side walls 4 of the slot 2 are spaced apart a distance substantially equal to the major diameter of the needle shank 6 so that the shank 6 can be positioned in the slot 2 with the major diameter transversely of the slot. The aperture 16 in the needle clamping body 15 is only large enough to permit the positioning face 12 to be moved away from the needle shank 6 a distance to provide for convenient in sertion of the shank and not a distance in which any point of the groove 13 is away from the bottom 3 of the slot 2 by an amount as great as the major diameter of the shank 6. Thus, the shank 6 can be accommodated in the slot 2 only when the major diameter is parallel to the bottom 3. More specifically, the aperture 16 has a diameter that is greater than the distance from the center point of the outer face 17 of the gib 9 and the opposite point of the needle bar 1, which is the diameter of the needle bar plus the amount that the gib protrudes beyond the needle bar, by an amount that is less than the difference between the major and minor diameters of the needle shank 6. In this manner, the gib 9 cannot be moved away from the needle shank a distance great enough to accommodate the needle shank in other than the correct sewing position.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claim.

Having thus set forth the nature of the invention, what I claim herein is:

In a sewing machine, a needle including a shank formed as a slab-sided circular cylinder having a major diameter and a minor diameter, a cylindrical needle bar having a flat-bottomed needle-shank-receiving slot extending endwise of said needle bar at the lower end thereof and a radial bore of a diameter greater than the width of said slot and intersecting said slot, said slot having a width substantially equal to the major diameter of said needle shank, and a needle clamp for securing said needle to said needle bar comprising a gib having a cylindrical portion disposed in said bore and a radially extending portion disposed in said slot, said cylindrical portion having a needle engaging face formed with a groove shaped to conform to the curved portion of said needle shank, said gib extending beyond the periphery of said slot when in needle clamping position, a needle clamp body loosely surrounding said needle bar about said gib for providing for movement of said gib out of needle clamping position and for limiting such movement to a distance less than the difierence between the major and minor diameters of said shank, said gib having a bore, a screw threaded through said needle clamp body and having a stud extending into the bore in said gib for securing said needle clamp body against movement endwise of the needle relatively to said gib, and a thumb screw threaded through said needle clamp body on the opposite side of the needle bar from said first mentioned screw and engaging said needle for tensioning said needle clamp body and pulling said gib into needle clamping position.

References Cited in the file of this patent UNITED STATES PATENTS 418,049 Muther Dec. 24, 1889 1,697,424 Greenwood Ian. 1, 1929 1,896,047 Grieb Jan. 31, 1933 2,088,852 Glasberg Aug. 3, 1937 2,698,589 Johnson Jan. 4, 1955 2,855,880 Johnson Oct. 14, 1958 FOREIGN PATENTS 301,763 Switzerland Dec. 1, 1954 

